Gamma-ray Irradiation Effects at 77K on Organic Materials Used in Superconducting Magnets for the J-PARC Neutrino Experiment (1 Mechanical Properties)

Radiation resistance with respect to mechanical properties of organic materials used in the superconducting magnets for the 50 GeV-750 kW proton beam line for the J-PARC neutrino experiment was studied. Specimens cooled at liquid nitrogen temperature of 77 K were irradiated by γ-rays from ^<60>Co up to 10 MGy. The flexural strength of glass-fiber reinforced plastics (GFRP) and the tear strength of polyimide films were evaluated. It was verified that the organic materials used in the superconducting magnet have a sufficient radiation resistance and degradation of the mechanical properties after 10 years operation was estimated to be negligible.